Question #adffa

2 Answers
Feb 18, 2018

#[-sin(x)tan(x)-cos(x)sec^2(x)]/tan^2(x)#

Explanation:

Assuming your problem is

#d/dx[(cos(x))/(tan(x))]#

Then, we have to use the quotient rule, which states that

#d/dx(x/y)=(color(red)(x')color(blue)y-color(green)xcolor(orange)(y'))/color(brown)(y^2)#

Here, let #x=cos(x)#, #y=tan(x)#

So, we get

#d/dx[(cos(x))/(tan(x))]=(color(red)(-sin(x))color(blue)(tan(x))-color(green)(cos(x))color(orange)(sec^2(x)))/color(brown)(tan^2(x))#

#dy/dx=(tanx(-sinx)-cosxsec^2x)/(tanx)^2#

#"We can simplify further if necessary":#

Explanation:

#"Let "y=cosx/tanx#

#"We need to apply [quotient rule]"#

(https://socratic.org/calculus/basic-differentiation-rules/quotient-rule)

#"Let" \ u=cosx, (du)/dx=-sinx#

#"Let" \ v=tanx, (dv)/dx=sec^2x#

#y=u/v, dy/dx=(v(du)/dx-u(dv)/dx)/v^2#

#"Substituting, we have"#

#dy/dx=(tanx(-sinx)-cosxsec^2x)/(tanx)^2#